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1 | package Time::HiRes; |
2 | |
3 | use strict; |
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4 | use vars qw($VERSION $XS_VERSION @ISA @EXPORT @EXPORT_OK $AUTOLOAD); |
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5 | |
6 | require Exporter; |
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7 | require DynaLoader; |
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8 | |
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9 | @ISA = qw(Exporter DynaLoader); |
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10 | |
11 | @EXPORT = qw( ); |
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12 | @EXPORT_OK = qw (usleep sleep ualarm alarm gettimeofday time tv_interval |
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13 | getitimer setitimer nanosleep |
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14 | ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF ITIMER_REALPROF |
15 | d_usleep d_ualarm d_gettimeofday d_getitimer d_setitimer |
16 | d_nanosleep); |
17 | |
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18 | $VERSION = '1.66'; |
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19 | $XS_VERSION = $VERSION; |
20 | $VERSION = eval $VERSION; |
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21 | |
22 | sub AUTOLOAD { |
23 | my $constname; |
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24 | ($constname = $AUTOLOAD) =~ s/.*:://; |
25 | die "&Time::HiRes::constant not defined" if $constname eq 'constant'; |
26 | my ($error, $val) = constant($constname); |
27 | if ($error) { die $error; } |
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28 | { |
29 | no strict 'refs'; |
30 | *$AUTOLOAD = sub { $val }; |
31 | } |
32 | goto &$AUTOLOAD; |
33 | } |
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34 | |
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35 | bootstrap Time::HiRes; |
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36 | |
37 | # Preloaded methods go here. |
38 | |
39 | sub tv_interval { |
40 | # probably could have been done in C |
41 | my ($a, $b) = @_; |
42 | $b = [gettimeofday()] unless defined($b); |
43 | (${$b}[0] - ${$a}[0]) + ((${$b}[1] - ${$a}[1]) / 1_000_000); |
44 | } |
45 | |
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46 | # Autoload methods go after =cut, and are processed by the autosplit program. |
47 | |
48 | 1; |
49 | __END__ |
50 | |
51 | =head1 NAME |
52 | |
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53 | Time::HiRes - High resolution alarm, sleep, gettimeofday, interval timers |
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54 | |
55 | =head1 SYNOPSIS |
56 | |
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57 | use Time::HiRes qw( usleep ualarm gettimeofday tv_interval nanosleep ); |
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58 | |
59 | usleep ($microseconds); |
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60 | nanosleep ($nanoseconds); |
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61 | |
62 | ualarm ($microseconds); |
63 | ualarm ($microseconds, $interval_microseconds); |
64 | |
65 | $t0 = [gettimeofday]; |
66 | ($seconds, $microseconds) = gettimeofday; |
67 | |
68 | $elapsed = tv_interval ( $t0, [$seconds, $microseconds]); |
69 | $elapsed = tv_interval ( $t0, [gettimeofday]); |
70 | $elapsed = tv_interval ( $t0 ); |
71 | |
72 | use Time::HiRes qw ( time alarm sleep ); |
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73 | |
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74 | $now_fractions = time; |
75 | sleep ($floating_seconds); |
76 | alarm ($floating_seconds); |
77 | alarm ($floating_seconds, $floating_interval); |
78 | |
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79 | use Time::HiRes qw( setitimer getitimer |
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80 | ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF ITIMER_REALPROF ); |
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81 | |
82 | setitimer ($which, $floating_seconds, $floating_interval ); |
83 | getitimer ($which); |
84 | |
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85 | =head1 DESCRIPTION |
86 | |
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87 | The C<Time::HiRes> module implements a Perl interface to the |
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88 | C<usleep>, C<nanosleep>, C<ualarm>, C<gettimeofday>, and |
89 | C<setitimer>/C<getitimer> system calls, in other words, high |
90 | resolution time and timers. See the L</EXAMPLES> section below and the |
91 | test scripts for usage; see your system documentation for the |
92 | description of the underlying C<nanosleep> or C<usleep>, C<ualarm>, |
93 | C<gettimeofday>, and C<setitimer>/C<getitimer> calls. |
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94 | |
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95 | If your system lacks C<gettimeofday()> or an emulation of it you don't |
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96 | get C<gettimeofday()> or the one-argument form of C<tv_interval()>. |
97 | If your system lacks all of C<nanosleep()>, C<usleep()>, and |
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98 | C<select()>, you don't get C<Time::HiRes::usleep()>, |
99 | C<Time::HiRes::nanosleep()>, or C<Time::HiRes::sleep()>. If your |
100 | system lacks both C<ualarm()> and C<setitimer()> you don't get |
101 | C<Time::HiRes::ualarm()> or C<Time::HiRes::alarm()>. |
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102 | |
103 | If you try to import an unimplemented function in the C<use> statement |
104 | it will fail at compile time. |
105 | |
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106 | If your subsecond sleeping is implemented with C<nanosleep()> instead |
107 | of C<usleep()>, you can mix subsecond sleeping with signals since |
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108 | C<nanosleep()> does not use signals. This, however, is not portable, |
109 | and you should first check for the truth value of |
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110 | C<&Time::HiRes::d_nanosleep> to see whether you have nanosleep, and |
111 | then carefully read your C<nanosleep()> C API documentation for any |
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112 | peculiarities. |
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113 | |
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114 | Unless using C<nanosleep> for mixing sleeping with signals, give |
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115 | some thought to whether Perl is the tool you should be using for |
116 | work requiring nanosecond accuracies. |
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117 | |
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118 | The following functions can be imported from this module. |
119 | No functions are exported by default. |
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120 | |
121 | =over 4 |
122 | |
123 | =item gettimeofday () |
124 | |
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125 | In array context returns a two-element array with the seconds and |
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126 | microseconds since the epoch. In scalar context returns floating |
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127 | seconds like C<Time::HiRes::time()> (see below). |
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128 | |
129 | =item usleep ( $useconds ) |
130 | |
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131 | Sleeps for the number of microseconds (millionths of a second) |
132 | specified. Returns the number of microseconds actually slept. Can |
133 | sleep for more than one second, unlike the C<usleep> system call. See |
134 | also C<Time::HiRes::usleep()> and C<Time::HiRes::sleep()>. |
135 | |
136 | Do not expect usleep() to be exact down to one microsecond. |
137 | |
138 | =item nanosleep ( $nanoseconds ) |
139 | |
140 | Sleeps for the number of nanoseconds (1e9ths of a second) specified. |
141 | Returns the number of nanoseconds actually slept (accurate only to |
142 | microseconds, the nearest thousand of them). Can sleep for more than |
143 | one second. See also C<Time::HiRes::sleep()> and |
144 | C<Time::HiRes::usleep()>. |
145 | |
146 | Do not expect nanosleep() to be exact down to one nanosecond. |
147 | Getting even accuracy of one thousand nanoseconds is good. |
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148 | |
149 | =item ualarm ( $useconds [, $interval_useconds ] ) |
150 | |
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151 | Issues a C<ualarm> call; the C<$interval_useconds> is optional and |
152 | will be zero if unspecified, resulting in C<alarm>-like behaviour. |
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153 | |
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154 | Note that the interaction between alarms and sleeps are unspecified. |
155 | |
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156 | =item tv_interval |
157 | |
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158 | tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] ) |
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159 | |
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160 | Returns the floating seconds between the two times, which should have |
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161 | been returned by C<gettimeofday()>. If the second argument is omitted, |
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162 | then the current time is used. |
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163 | |
164 | =item time () |
165 | |
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166 | Returns a floating seconds since the epoch. This function can be |
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167 | imported, resulting in a nice drop-in replacement for the C<time> |
168 | provided with core Perl; see the L</EXAMPLES> below. |
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169 | |
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170 | B<NOTE 1>: This higher resolution timer can return values either less |
171 | or more than the core C<time()>, depending on whether your platform |
172 | rounds the higher resolution timer values up, down, or to the nearest second |
173 | to get the core C<time()>, but naturally the difference should be never |
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174 | more than half a second. |
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175 | |
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176 | B<NOTE 2>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT, when |
177 | the C<time()> seconds since epoch rolled over to 1_000_000_000, the |
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178 | default floating point format of Perl and the seconds since epoch have |
179 | conspired to produce an apparent bug: if you print the value of |
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180 | C<Time::HiRes::time()> you seem to be getting only five decimals, not |
181 | six as promised (microseconds). Not to worry, the microseconds are |
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182 | there (assuming your platform supports such granularity in the first |
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183 | place). What is going on is that the default floating point format of |
184 | Perl only outputs 15 digits. In this case that means ten digits |
185 | before the decimal separator and five after. To see the microseconds |
186 | you can use either C<printf>/C<sprintf> with C<"%.6f">, or the |
187 | C<gettimeofday()> function in list context, which will give you the |
188 | seconds and microseconds as two separate values. |
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189 | |
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190 | =item sleep ( $floating_seconds ) |
191 | |
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192 | Sleeps for the specified amount of seconds. Returns the number of |
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193 | seconds actually slept (a floating point value). This function can |
194 | be imported, resulting in a nice drop-in replacement for the C<sleep> |
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195 | provided with perl, see the L</EXAMPLES> below. |
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196 | |
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197 | Note that the interaction between alarms and sleeps are unspecified. |
198 | |
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199 | =item alarm ( $floating_seconds [, $interval_floating_seconds ] ) |
200 | |
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201 | The C<SIGALRM> signal is sent after the specified number of seconds. |
202 | Implemented using C<ualarm()>. The C<$interval_floating_seconds> argument |
203 | is optional and will be zero if unspecified, resulting in C<alarm()>-like |
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204 | behaviour. This function can be imported, resulting in a nice drop-in |
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205 | replacement for the C<alarm> provided with perl, see the L</EXAMPLES> below. |
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206 | |
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207 | B<NOTE 1>: With some combinations of operating systems and Perl |
208 | releases C<SIGALRM> restarts C<select()>, instead of interrupting it. |
209 | This means that an C<alarm()> followed by a C<select()> may together |
210 | take the sum of the times specified for the the C<alarm()> and the |
211 | C<select()>, not just the time of the C<alarm()>. |
212 | |
213 | Note that the interaction between alarms and sleeps are unspecified. |
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214 | |
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215 | =item setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] ) |
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216 | |
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217 | Start up an interval timer: after a certain time, a signal arrives, |
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218 | and more signals may keep arriving at certain intervals. To disable |
219 | an "itimer", use C<$floating_seconds> of zero. If the |
220 | C<$interval_floating_seconds> is set to zero (or unspecified), the |
221 | timer is disabled B<after> the next delivered signal. |
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222 | |
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223 | Use of interval timers may interfere with C<alarm()>, C<sleep()>, |
224 | and C<usleep()>. In standard-speak the "interaction is unspecified", |
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225 | which means that I<anything> may happen: it may work, it may not. |
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226 | |
227 | In scalar context, the remaining time in the timer is returned. |
228 | |
229 | In list context, both the remaining time and the interval are returned. |
230 | |
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231 | There are usually three or four interval timers available: the |
232 | C<$which> can be C<ITIMER_REAL>, C<ITIMER_VIRTUAL>, C<ITIMER_PROF>, or |
233 | C<ITIMER_REALPROF>. Note that which ones are available depends: true |
234 | UNIX platforms usually have the first three, but (for example) Win32 |
235 | and Cygwin have only C<ITIMER_REAL>, and only Solaris seems to have |
236 | C<ITIMER_REALPROF> (which is used to profile multithreaded programs). |
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237 | |
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238 | C<ITIMER_REAL> results in C<alarm()>-like behavior. Time is counted in |
239 | I<real time>; that is, wallclock time. C<SIGALRM> is delivered when |
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240 | the timer expires. |
241 | |
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242 | C<ITIMER_VIRTUAL> counts time in (process) I<virtual time>; that is, |
243 | only when the process is running. In multiprocessor/user/CPU systems |
244 | this may be more or less than real or wallclock time. (This time is |
245 | also known as the I<user time>.) C<SIGVTALRM> is delivered when the |
246 | timer expires. |
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247 | |
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248 | C<ITIMER_PROF> counts time when either the process virtual time or when |
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249 | the operating system is running on behalf of the process (such as I/O). |
250 | (This time is also known as the I<system time>.) (The sum of user |
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251 | time and system time is known as the I<CPU time>.) C<SIGPROF> is |
252 | delivered when the timer expires. C<SIGPROF> can interrupt system calls. |
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253 | |
254 | The semantics of interval timers for multithreaded programs are |
255 | system-specific, and some systems may support additional interval |
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256 | timers. See your C<setitimer()> documentation. |
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257 | |
258 | =item getitimer ( $which ) |
259 | |
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260 | Return the remaining time in the interval timer specified by C<$which>. |
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261 | |
262 | In scalar context, the remaining time is returned. |
263 | |
264 | In list context, both the remaining time and the interval are returned. |
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265 | The interval is always what you put in using C<setitimer()>. |
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266 | |
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267 | =back |
268 | |
269 | =head1 EXAMPLES |
270 | |
271 | use Time::HiRes qw(usleep ualarm gettimeofday tv_interval); |
272 | |
273 | $microseconds = 750_000; |
274 | usleep $microseconds; |
275 | |
276 | # signal alarm in 2.5s & every .1s thereafter |
277 | ualarm 2_500_000, 100_000; |
278 | |
279 | # get seconds and microseconds since the epoch |
280 | ($s, $usec) = gettimeofday; |
281 | |
282 | # measure elapsed time |
283 | # (could also do by subtracting 2 gettimeofday return values) |
284 | $t0 = [gettimeofday]; |
285 | # do bunch of stuff here |
286 | $t1 = [gettimeofday]; |
287 | # do more stuff here |
288 | $t0_t1 = tv_interval $t0, $t1; |
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289 | |
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290 | $elapsed = tv_interval ($t0, [gettimeofday]); |
291 | $elapsed = tv_interval ($t0); # equivalent code |
292 | |
293 | # |
294 | # replacements for time, alarm and sleep that know about |
295 | # floating seconds |
296 | # |
297 | use Time::HiRes; |
298 | $now_fractions = Time::HiRes::time; |
299 | Time::HiRes::sleep (2.5); |
300 | Time::HiRes::alarm (10.6666666); |
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301 | |
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302 | use Time::HiRes qw ( time alarm sleep ); |
303 | $now_fractions = time; |
304 | sleep (2.5); |
305 | alarm (10.6666666); |
306 | |
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307 | # Arm an interval timer to go off first at 10 seconds and |
308 | # after that every 2.5 seconds, in process virtual time |
309 | |
310 | use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time ); |
311 | |
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312 | $SIG{VTALRM} = sub { print time, "\n" }; |
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313 | setitimer(ITIMER_VIRTUAL, 10, 2.5); |
314 | |
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315 | =head1 C API |
316 | |
317 | In addition to the perl API described above, a C API is available for |
318 | extension writers. The following C functions are available in the |
319 | modglobal hash: |
320 | |
321 | name C prototype |
322 | --------------- ---------------------- |
323 | Time::NVtime double (*)() |
324 | Time::U2time void (*)(UV ret[2]) |
325 | |
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326 | Both functions return equivalent information (like C<gettimeofday>) |
327 | but with different representations. The names C<NVtime> and C<U2time> |
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328 | were selected mainly because they are operating system independent. |
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329 | (C<gettimeofday> is Unix-centric, though some platforms like VMS have |
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330 | emulations for it.) |
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331 | |
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332 | Here is an example of using C<NVtime> from C: |
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333 | |
334 | double (*myNVtime)(); |
335 | SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12, 0); |
336 | if (!svp) croak("Time::HiRes is required"); |
337 | if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer"); |
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338 | myNVtime = INT2PTR(double(*)(), SvIV(*svp)); |
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339 | printf("The current time is: %f\n", (*myNVtime)()); |
340 | |
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341 | =head1 DIAGNOSTICS |
342 | |
343 | =head2 negative time not invented yet |
344 | |
345 | You tried to use a negative time argument. |
346 | |
347 | =head2 internal error: useconds < 0 (unsigned ... signed ...) |
348 | |
349 | Something went horribly wrong-- the number of microseconds that cannot |
350 | become negative just became negative. Maybe your compiler is broken? |
351 | |
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352 | =head1 CAVEATS |
353 | |
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354 | Notice that the core C<time()> maybe rounding rather than truncating. |
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355 | What this means is that the core C<time()> may be reporting the time |
356 | as one second later than C<gettimeofday()> and C<Time::HiRes::time()>. |
357 | |
358 | Adjusting the system clock (either manually or by services like ntp) |
359 | may cause problems, especially for long running programs that assume |
360 | a monotonously increasing time (note that all platforms do not adjust |
361 | time as gracefully as UNIX ntp does). For example in Win32 (and derived |
362 | platforms like Cygwin and MinGW) the Time::HiRes::time() may temporarily |
363 | drift off from the system clock (and the original time()) by up to 0.5 |
364 | seconds. Time::HiRes will notice this eventually and recalibrate. |
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365 | |
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366 | =head1 AUTHORS |
367 | |
368 | D. Wegscheid <wegscd@whirlpool.com> |
369 | R. Schertler <roderick@argon.org> |
370 | J. Hietaniemi <jhi@iki.fi> |
371 | G. Aas <gisle@aas.no> |
372 | |
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373 | =head1 COPYRIGHT AND LICENSE |
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374 | |
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375 | Copyright (c) 1996-2002 Douglas E. Wegscheid. All rights reserved. |
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376 | |
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377 | Copyright (c) 2002,2003,2004 Jarkko Hietaniemi. All rights reserved. |
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378 | |
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379 | This program is free software; you can redistribute it and/or modify |
380 | it under the same terms as Perl itself. |
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381 | |
382 | =cut |